Conduits, or drainage tubes, are commonly employed with fuel tanks, such as may exist on aircraft, for the purpose of draining fuel. Such tubes normally have a smooth cylindrical end which extends from the associated tank. Often, the situation arises where it is necessary that the fuel drained from the tank be transferred to another tank, or that the drainage tube be used for the purpose of refueling, in which case it is necessary to connect a hose line to the drainage tube. Currently, in order to connect a hose line to a smooth wall a hose clamp must be used which is applied around the hose line and the tube and tightened thereon. While hose clamps have proven to provide a relatively leak-free connection between the hose line and conduit they are not capable of being quickly applied or removed. Also, it is not possible to utilize a hose clamp to connect a hose line to a conduit when the conduit and hose line are of substantially different diameters.
It is therefore an object of the invention to provide a fitting which can be installed over the end of a smooth wall conduit and secured thereon, wherein the fitting is capable of being quickly connected or disconnected to a standard adapter mounted on the end of a hose line, which may be of a different diameter than the conduit, to place the conduit and hose line in fluid communication.
It is another object of the invention to provide a fitting to be installed over the end of a smooth wall conduit wherein the fitting itself is capable of being quickly and easily installed and removed and wherein the fitting establishes a fluid tight seal with the outer surface of the conduit, even if it is not completely smooth, to allow fluid to flow freely in the fitting in either direction without leakage.
It is a further object of the invention to provide a fitting to be installed over the end of a smooth wall conduit which is connectable to an adapter mounted on the end of a hose line to establish a fluid passage between the hose and conduit, wherein the fitting is provided with a safety strap assembly to prevent premature disconnection of the fitting from the conduit in the event of internal pressure surges.
It is yet a further object of the invention to provide a fitting to be installed over the end of a smooth wall conduit having an adapter attachment end for coupling to a separate adapter wherein the fitting employs a dust cap assembly which may be mounted to the attachment end when the adapter is removed to prevent foreign matter from entering the fitting and conduit.
In the practice of the invention a fitting includes a body having an axial passage extending therethrough between a conduit attachment end and an open end. The conduit attachment end is installed over the end of a conduit or drainage tube, such as the type commonly employed with fuel tanks of aircraft, and an adapter attachment is threadedly mounted on the body open end having an axial passage in alignment with the body passage. The adapter attachment includes a collar assembly which is adapted to connect to a standard unisex adapter mounted on the end of a hose line. A plurality of circumferentially spaced slots are formed in the body adjacent the conduit end, and each slot is provided with a ball which is permitted to slightly extend into the body passage. A sleeve is slidably mounted on the conduit end displaceable between a release position and a lock position whereby a retainer mounted on the sleeve forces the balls radially inwardly into engagement with the associated conduit's smooth wall to secure the fitting to the conduit. A spring interposed between the body and sleeve normally biases the sleeve to the lock position.
The fitting is provided with a strap assembly, which includes a hook receivable in an eye mounted on the tank from which the associated conduit extends to prevent the fitting from being blown off the conduit in the event of internal pressure surges, and a dust cap assembly which is adapted to be mounted over the adapter attachment when the unisex adapter is removed to prevent foreign matter from entering the fitting and conduit. A web type annular seal disposed on the interior of the fitting body establishes a fluid tight seal with the outer surface of the associated conduit even if the cylindrical surface of the conduit is not completely smooth.
To install the fitting on the conduit the sleeve is manually displaced to the release position and the fitting conduit end is aligned with the end of the conduit and slidably mounted thereon. As the fitting is axially displaced on the conduit the fitting internal web seal contacts and passes over the end of the conduit establishing a sealing relationship with the smooth surface, and assembly is complete when the seal has passed the conduit end by a substantial distance. At this time, releasing the sleeve causes the sleeve to move toward the lock position, due to the biasing force of the spring, forcing the balls radially inwardly whereby the balls engage and slightly burnell with the conduit's outer surface to prevent the fitting from sliding off the conduit. Installation is complete when the operator connects the strap assembly hook to the tank eye and draws the strap assembly tight.
Once installed, a standard unisex adapter mounted on the end of a hose line can be connected to the attachment end of the fitting to place the conduit in fluid communication with the hose line and fluid may flow through the fitting in either direction. Preferably, when the unisex adapter is removed the dust cap is mounted on the attachment end to prevent foreign matter from entering the fitting and possibly damaging the seals.
The fitting may be removed from the conduit by first removing the strap assembly hook from the tank eye and then displacing the sleeve to the release position and pulling the fitting body from the conduit.
The balls are constructed of a matte finished stainless steel substantially harder than the associated conduit surface to permit the balls to burnell into the conduit, and the length of the slots are substantially greater than the diameter of the balls to permit the balls limited movement in the axial direction of the fitting allowing the sleeve to impose a greater force on the balls. The spring must be of a sufficient force to slightly burnell the balls into the associated conduit via the sleeve but still be able to be compressed by manual force applied by the operator.